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Dagster webserver

The Dagster webserver serves the Dagster UI, a web-based interface for viewing and interacting with Dagster objects. It also responds to GraphQL queries.

In the UI, you can inspect Dagster objects (ex: assets, jobs, schedules), launch runs, view launched runs, and view assets produced by those runs.

Launching the webserver​

The easiest way to launch the webserver from the command line during local development is to run:

dagster dev

This command launches both the Dagster webserver and the Dagster daemon, allowing you to start a full local deployment of Dagster from the command line.

The command will print out the URL you can access the UI from in the browser, usually on port 3000.

When invoked, the webserver will fetch definitions - such as assets, jobs, schedules, sensors, and resources - from a Definitions object in a Python module or package or the code locations configured in an open source deployment's workspace files. For more information, see the code locations documentation.

You can also launch the webserver by itself from the command line by running:

dagster-webserver

Note that several Dagster features, like schedules and sensors, require the Dagster daemon to be running in order to function.

Overview page​

  • Description: This page, also known as the "factory floor", provides a high-level look at the activity in your Dagster deployment, across all code locations. This includes information about runs, jobs, schedules, sensors, resources, and backfills, all of which can be accessed using the tabs on this page.

  • Accessed by: Clicking Overview in the top navigation bar

The Overview tab, also known as the Factory Floor, in the Dagster UI

Assets​

Asset catalog (OSS)

  • Description: The Asset catalog page lists all assets in your Dagster deployment, which can be filtered by asset key, compute kind, asset group, code location, and tags. Clicking an asset opens the Asset details page for that asset. You can also navigate to the Global asset lineage page, reload definitions, and materialize assets.

  • Accessed by: Clicking Assets in the top navigation bar

The Asset Catalog page in the Dagster UI

Runs​

All runs

  • Description: The Runs page lists all job runs, which can be filtered by job name, run ID, execution status, or tag. Click a run ID to open the Run details page and view details for that run.

  • Accessed by: Clicking Runs in the top navigation bar

UI Runs page

Schedules​

All schedules

  • Description: The Schedules page lists all schedules defined in your Dagster deployment, as well as information about upcoming ticks for anticipated scheduled runs. Click a schedule to open the Schedule details page.

  • Accessed by: Clicking Overview (top nav) > Schedules tab

UI Schedules page

Sensors​

All sensors

  • Description: The Sensors page lists all sensors defined in your Dagster deployment, as well as information about the sensor's frequency and its last tick. Click a sensor to view details about the sensor, including its recent tick history and recent runs.

  • Accessed by: Clicking Overview (top nav) > Sensors tab

UI Sensors page

Resources​

All resources

  • Description: The Resources page lists all resources defined in your Dagster deployment, across all code locations. Clicking a resource will open the Resource details page.

  • Accessed by: Clicking Overview (top nav) > Resources tab

UI Resources page

Backfills​

  • Description: The Backfills tab contains information about the backfills in your Dagster deployment, across all code locations. It includes information about when the partition was created, its target, status, run status, and more.

  • Accessed by: Clicking Overview (top nav) > Backfills tab

UI Backfills tab

Jobs​

All jobs

  • Description: The Jobs page lists all jobs defined in your Dagster deployment across all code locations. It includes information about the job's schedule or sensor, its latest run time, and its history. Click a job to open the Job details page.

  • Accessed by: Clicking Overview (top nav) > Jobs tab

UI Job Definition

Deployment​

The Deployment page includes information about the status of the code locations in your Dagster deployment, daemon (Open Source) or agent (Cloud) health, schedules, sensors, and configuration details.

Code locations tab

  • Description: The Code locations tab contains information about the code locations in your Dagster deployment, including their current status, when they were last updated, and high-level details about the definitions they contain. You can reload Dagster definitions by:

    • Clicking Reload all to reload all definitions in all code locations
    • Clicking Reload next to a specific code location to reload only that code location's definitions

  • Accessed by:

    • Clicking Deployment in the top navigation bar
    • On the Deployment overview page, clicking the Code locations tab

UI Deployment overview page